Speed Tech Performance Track Time Kit - Second to None

Speed Tech Performance’s Track Time Kit Changes the Way ’70– 81 F-bodies Handle for the Better … Without Changing the Whole Car

As it stands, most A-arm front suspensions on rear-drive cars have a little bit of positive scrub radius (the tire centerline lies outboard of the SAI). Dropping a knuckle simply by moving its wheel-mounting point upwards increases the positive scrub radius; however, moving it along the SAI preserves the scrub radius. The same goes for a hub or brake hat that pushes the wheel out: it moves the scrub radius more positive. Speed Tech accounted for that, too.

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Speed Tech used the divorced steering arm design to solve another problem associated with scrub radius. Anyone who’s ever tried to bolt wider wheels to a second-gen Camaro can bear testimony that the tie rod location limits rim width and ultimately offset. Most enthusiasts simply fit a wheel with more negative offset (add more of the width to the wheel face). That, too, makes the scrub radius more positive.

Well, Speed Tech worked too hard to preserve geometry just to throw it away on a wheel-offset compromise. So it eliminated the interference between the tie-rod end and the wheel by shortening the steering arm.

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The clearance gained makes it possible to maintain the OEM-style wheel offsets when using wider wheels. For a baseline, consider that GM equipped most first- and second-gen Camaros with wheels that have a 0.25-inch (6.35mm) offset. Speed Tech designed the arm to fit a 17x9.5 wheel with at least 5.5 inches of backspace and a 20x10 wheel with at least 6 inches of backspace. Both examples maintain the same 0.25-inch offset as the OEM wheel. Correct-offset wheels offer another bonus: they’re less likely to interfere with the fender opening.

The shorter arm also speeds up the steering ratio in the same way a numerically lower steering box ratio does. Speed Tech takes it one step further by including in their kit a super-fast Lee Manufacturing 12.7:1 power steering box. But a shorter steering arm has one potentially negative consequence: it increases the angle from the tie rod to the steering arm.

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Increasing that angle reduces the Ackerman effect, the dynamic that lets each steering wheel follow its own radius as the car turns. However, Speed Tech restored that angle and the Ackerman by moving the steering arm’s tie-rod pick-up point away from the car’s centerline.

And remember the bumpsteer issues mentioned? Speed Tech solved that with the revised steering-arm design. Moving the tie-rod mounting point down a smidgen reduced bumpsteer to 0.02-inch at full compression and 0.01-inch at full droop. But it didn’t solve it consistently on all cars.

The reason for the inconsistency is because not all F-bodies were created equal. GM equipped them with different parts depending on model and make (remember the Firebird?). And while those cars may have left the factory with matching parts, they may not have gotten the correct replacements over the years. So instead of accounting for potentially dozens of variations of matched parts, Speed Tech designed its suspension around a particular set of OEM and replacement parts, which it supplies with the kits. It even found the opportunity to correct a flaw inherent in the factory design with an offset idler-arm bracket that levels the drag link.

Though knuckles distinguish Speed Tech’s system, it should be obvious by now that they’re really only a part in an assembly: the kit includes special control arms and two coilover/damper options sprung and tuned specifically for the application. But by engineering everything around those parts, the company has created an entire system where everything works together to achieve a specific goal: superlative handling.

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Admittedly, these system-engineered suspensions aren’t a new idea; they’ve evolved to the point that some manufacturers dispense with factory subframes for custom ones. However, this one vastly improves handling by a somewhat traditional way: by preserving the vehicle’s chassis and as many of the OEM-style parts as possible. It’s certainly a factor in purchase price, but it facilitates long-term serviceability.

So you could say the Track Time kit is one that you and your wallet can enjoy.

1. The lateral position of the upper ball joint between the knuckles isn’t obvious, but the height is: the AFX versions drop the car about an inch. The construction is also obvious: it uses a Corvette C5/C6 hub (shown with optional long studs for track use).

3. The shorter steering arm has two consequences: improves the steering response and it accommodates wider wheels at the correct offset. It altered the Ackerman effect, but the photo showing the knuckles facing each other reveals how Speed Tech corrected it by decreasing the tie-rod angle by moving the tie-rod ends further from the vehicle’s centerline.

4. Here’s something to drive home the weight point. Though the assembly on the right has a 14-inch diameter rotor and a six-pot caliper (both optional), it still weighs less than the stock knuckle with the 11-inch rotor. Any reduction of unsprung mass improves suspension response.

6. Speed Tech loads its tubular control arms with Acetal (commonly known by DuPont’s trade name, Delrin) bushings. While Acetal bushings are self-lubricating and won’t squeak even when dry, Speed Tech equips the shells with grease fittings.

7. This bracket is actually specific to the coilover dampers. It replaces the conventional damper upper brackets and fortifies the upper control-arm mounts.

10. As noted earlier, the AFX knuckle is a hair shorter than GM’s. But the difference is so slight that it can be addressed by slotting the upper control arm mounting points downward by the same amount.

12. These pitman arms differ even though they came from two identically equipped F-body cars. Only the one in the background works with the kit, hence the reason Speed Tech supplies it with the kits.

13. Speed Tech discovered variations in idler arms with the same part number hence the reason it supplies this arm. The included bracket lowers the arm, which levels the drag link and equalizes bumpsteer on both sides.

14. It’s logical to assume that raising the pitman side and dropping the idler side of the drag link would disrupt things, but that assumes it was correct from the start. As this photo shows, the centerline remains perfectly consistent with the other suspension pick-up points with the Speed Tech parts.

15. The antiroll bar employs a conventional endlink, but tubular arms don’t lend themselves to the design. So Speed Tech took the opportunity to use a more precise spherical rod end instead.

16. The tie-rod end isn’t the only factor that limits wheel offset. Tires on wider wheels with lots of backspace hit the bar as shown here. So Speed Tech is working with a manufacturer right now on a modified bar. It should be ready by the time this issue hits newsstands.

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